M. M. Sitnikov, Ionic Processes and Some of Their Technical Applications. Proceedings of the State Physico-Technical Laboratory. Issue 7. Published by the Scientific-Technical Administration of the Supreme Council of National Economy of the USSR. Moscow. 1929.

In M. M. Sitnikov’s work, the following are chiefly considered: 1) the passage of electric current through a gaseous medium in the case when the mean free path of an electron is several times greater than, or of the same order as, the distance between the electrodes; 2) methods of controlling gas conductivity; and 3) a number of practical applications in the form of gas converters, mainly for rectification and for the generation of high- and radio-frequency oscillations.

The author has carried out a deeper analysis of the phenomenon of conductivity in a gaseous medium than had previously been done, taking into account not only the free path of the electron and the distance between the electrodes, but also the relation between the electrical and thermal velocities of molecules and electrons. Special consideration is given to the phenomenon of current passage in mercury vapor, and a connection is found between the minimum of losses and the approximate equality between the mean electrical and mean thermal velocities of the moving electrons.

The diagrams of electron motion presented in the work make it possible to determine the conductivity zone for plane electrodes in the absence of space charges. In addition, the electron trajectory has been approximately determined for the same case of plane electrodes, but in the presence of space charges, and thus a step has been taken toward obtaining a solution for this case, which is important from the technical point of view. Analogous results have also been obtained for the case of cylindrical coaxial electrodes. The data presented on these questions make it possible to approach the solution of a number of technical problems, as the author has done in subsequent chapters, in which he describes a number of constructed devices together with some data from their testing.

Besides these most fully developed questions, the work by M. M. Sitnikov also contains a number of other, less fully developed but important propositions that characterize the originality of the author’s views on the nature of ionization in more complex cases. In particular, the work contains a number of valuable indications concerning phenomena occurring in mercury rectifiers, in solid and liquid dielectrics during their ionization, and also in vacuum tubes at very high rarefactions.

Devoted to consideration of questions whose solution is at present occupying the largest laboratories abroad—chiefly in the United States of America—this work provides new and valuable material and naturally should attract the attention of specialists to the further study of ionic processes, whose technical utilization promises still broader practical application than that which we have in electronic devices, without the shortcomings that are found

in the latter, and which are connected with the presence in them of charges of one sign.

The originality, rigorous yet at the same time sufficiently accessible exposition makes the appearance of this work highly timely.

M. Lapirov-Skoblo.